1. Field of Invention
This invention relates to an ink jet printer, and particularly to nonbuttable full-width array printbars, and more particularly to reducing the number of nonbuttable full-width array printbars required in a color printer by including one printbar with multicolor die modules or by staggering printbars with multicolor die modules between printbars with single color die modules.
2. Description of Related Art
In an ink jet printing apparatus, individual drops of ink are ejected from a nozzle such that the droplet of ink travels under its own momentum towards a sheet of paper or other print medium on which drops of ink are intended to fall, with the impact areas overlapping so that they form characters or other marks of desired shape. In the ink jet printing apparatus, a printhead including a printbar with several die modules may be used with a plurality of individual nozzles in which to dispel the ink droplets. Such printheads are scanned across the medium to be marked in order to print the entire page.
Alternatively, with a page-width printhead, the printhead is stationary and dispels ink onto the medium from the top of the medium to the bottom. With a page-width printhead, the printhead will include a full-width printbar with several die modules accurately positioned with respect to each other so that the line of picture elements (pixels) produced by printed droplets from neighboring modules show no seams, and the pixels appear to be produced by one continuous line of uniformly spaced ink drop nozzles. An ink may be deposited onto the print medium one line at a time by the full-width printbar as the paper passes by until full-page images are completed. This type of ink jet printing process uses a single pass method and is known as a xe2x80x9cfull-width arrayxe2x80x9d printer.
Various methods are known for fabricating full-width array printbars. One method is to form a linear pagewidth printbar by providing end-to-end abutment of fully functional printhead elements (die modules) on a substrate. This type of arrangement is termed buttable or butted. In other words, each of the die modules are positioned joined end to end with respect to each other such that the die modules together make up the print region of the print medium. The die modules are positioned end to end so that the pixels produced by neighboring modules show no seams, and the pixels appear to be produced by one continuous line of uniformly spaced ink drop nozzles. U.S. Pat. Nos. 5,192,959, 4,999,077, and 5,198,054 disclose processes for forming linear printbars of butted subunits.
Because each of the die modules are positioned joined end to end with respect to each other on a single substrate such that the die modules together make up the print region of the print medium, only one full width printbar is necessary, for example, with a black ink only system. Additional full-width color printbars may be added to enable a highlight or full color printer.
In a multi-color ink jet printing process, several full-width array printbars are used in a printer to deposit different color inks onto a print medium to give full color images. The different color inks comprise, for example, black, cyan, magenta, and yellow inks.
U.S. Pat. Nos. 5,280,308, 5,343,227, and 5,270,738 disclose full color pagewidth printers with four printbars, black, cyan, magenta, and yellow.
However, in a full-width array printbar with die modules abutted end to end, the joints between successive die modules make it difficult to accurately and precisely print on a print medium.
Another method for fabricating a full-width printbar is to provide same color die modules as two separated printbars. This type of arrangement is referred to as nonbuttable as the die modules of the printbars are not abutting each other. Die modules of the first printbar are spaced substantially evenly apart, creating a gap between each of the die modules. Die modules of the same output color are then located on the second printbar in a spaced apart manner such that they align with the gaps between the die modules on the first printbar. The die modules of the two printbars thus overlap so that the die modules of the two printbars together make up the print region of the print medium. In other words, the die modules of the two printbars are staggered to form a checker board pattern, but also overlap each other. For this arrangement, two printbars are required for each color to be printed. Thus, for a four-color printer, for example, eight printbars are required.
FIG. 1 shows such a typical printhead configuration 10 for a four-color nonbuttable full-width array printer. Two printbars (i.e., two halfbars 12) for each of the four colors, cyan (C), magenta (M), yellow (Y) and black (K) for a total of eight halfbars 12 are illustrated. In FIG. 1, six die modules 22 are provided on each halfbar, and twelve die modules 22 are provided for each color. The printing length of each die module is L. Because there is some overlap of die modules 22 from each complementary halfbar for each color, the overall printing length P is a little less than the length of all twelve die modules.
More specifically, the total allowable printing length P (preferably the width of the paper being printed) is printed using the two complementary staggered halfbars 12 for each color. Each of the plurality of die modules 22 on each halfbar 12 has a printing length L. The spacing between each of the plurality of die modules 22 also has a length of L, or more typically a little less than L, in order to allow some overlap between the die modules 22 of the two complementary staggered halfbars 12. Thus, a stitch between the die modules 22 is less obvious by printing half pixels near the stitch from one of the die modules 22 and the other half of the pixels by the complementary die module 22 on the other halfbar 12. Usually the gap between printing sections of adjacent modules on the same halfbar 12 is not completely empty. Typically, one of the die modules 22 extends beyond the last printing nozzle on each end of the printbar, and typically the ends of an ink manifold (not shown) extend beyond the ends of each of the die modules 22.
A consideration when designing a pagewidth color printer is the cost and maintenance of the full width printbars. Thus, reducing the number of required printbars would reduce cost as well as result in a more compact printer.
There is a need for a reduction in the number of nonbuttable full-width array printbars required in a printhead of a color printer.
There is also a need to simplify the ink delivery system of color printers with nonbuttable full-width array printbars.
There is further a need to increase the speed of color printers without detracting from the color integrity or uniformity of the image printed.
There is also a need for a color printer with nonbuttable full-width array printbars with enhanced colors for printed color images and having a fuller range of colors.
There is further a need for a color printer with nonbuttable full-width array printbars with fewer parts for an overall more compact structure.
There is a need to simplify maintenance of a color printer with nonbuttable full-width array printbars.
There is a need to reduce costs associated with maintenance of a color printer with nonbuttable full-width array printbars.
The above and other advantages are achieved by various embodiments of the invention.
In exemplary embodiments, fewer parts are required for a more compact printer structure.
In exemplary embodiments, the configuration of the printbars may provide enhanced color images.
In exemplary embodiments, problems associated with the ink delivery system of nonbuttable full-width array printbars may be improved.
In exemplary embodiments, the configuration of the printbars may provide greater uniformity of colors with fewer parts.
In exemplary embodiments, the configuration of the printbars may provide greater integrity of colors with fewer parts.